152 



HUGH WATSON. 



The Nervous System as a Whole. — It will have been 

 seen from the above account that the central nervous system 

 of Apera may be regarded as formed of five sections, each 



Text-fig. 2. 



f Cerel.ral. ^ Pedal. 



■i Buccal. C] Pleural. 



^ Visceral. 



Diagram of the central nervous system of Apera. 



with a single pair of ganglia. These five sections are dia- 

 grammatically represented in the accompanying text-figure. 

 There is first the buccal section, which is the most anterior 

 only in A. burnupi and A. sexangula. This innervates 

 the anterior part of the alimentary canal, including the 

 odontophore and salivary glands. Secondly, there is the 



